Conventionally, a terminal-modified polybutadiene or terminal-modified hydrogenated polybutadiene in which a functional group, such as a hydroxyl group or a carboxyl group, is bonded to a terminal portion of the main chain of a polybutadiene or hydrogenated polybutadiene has been known. The terminal-modified polybutadiene or terminal-modified hydrogenated polybutadiene becomes a resin that has excellent water and moisture resistance, chemical resistance, electrical characteristics (high dielectric strength, low dielectric constant, and arc resistance), and transparency, and exhibits physical properties including high toughness, by curing.
Further, polymer oligomers in which a functional group, such as a hydroxyl group, of a polymer is modified with a polymerizable functional group, such as an acryloyl group or a methacryloyl group, via a urethane bond in order to increase curability with ultraviolet rays or electron beams have been developed, and applications to new uses have been expected.
As a method for producing a terminal-modified polybutadiene or terminal-modified hydrogenated polybutadiene (D), an industrial production method in which an isocyanate compound (A) and a polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal (B) are reacted in the presence of dibutyl tin dilaurate (C) has been known (Patent Document 1).

In addition, Patent Document 2 discloses that by using an organobismuth compound or a tetraalkoxyzirconium compound as a catalyst instead of a dibutyl tin dilaurate catalyst, a composition that is more environmentally friendly and has better storage stability is obtained.